Machine regulation of a high-output generator having the starting function of a three-phase current synchronous machine requires information on the load angle (pole wheel position angle). If incremental encoders are used, recording the load angle is possible only in moved/rotating systems. However, to make available maximum torque, for example at the starting of the internal combustion engine, information on the pole wheel position is already required at a rotational speed n=0.
A system for reducing torsional vibrations in the power train may be seen in the journal xe2x80x9cSystem Partner 98xe2x80x9d, pages 64 to 66. The system combines two electrical machines in itself, which are used on the one hand for the xe2x80x9cstartxe2x80x9d function, and on the other hand for voltage supply in the vehicle electrical system of motor vehicles. Using the proposed design approach, the power of the electrical machine may be used to apply torque impulses to the crankshaft of the internal combustion engine, so that noticeable rotational irregularities may be minimized.
The electrical machine used generates a great acceleration of the crank mechanism, the internal combustion engine being accelerated to idling speed; only after that, does ignition take place. The generator function of the system offers high electrical power even at very low rotational speeds; the three-phase machine is driven from a pulse-controlled inverter, and therefore, with respect to its rotational speed and its torque, it is able to be freely controlled and regulated.
A method for estimating the pole wheel position in a claw pole machine may be seen in German Patent Application No. DE 100 36 869. This relates to a method for determining the position of a rotating component of a claw pole machine which is operated in the RST system, and for whose regulation the transformation of the stator variables from the RST system into the d, q system and vice versa is required. The claw pole machine as an overall system is subdivided into a non-observable subsystem and an observable subsystem containing a filter element. The filter element contained in the observable subsystem delivers the output variables.
The method permits the determination of the pole wheel position only when the internal combustion engine is rotating, so that the search cycle prolongs the starting process inadmissibly when a high-output generator is used, and again partially reduces to nothing the driving advantage achievable by the use of these high-output machines.
Using the method according to the present invention, in the ideal case the search cycle may be completely eliminated by evaluating data that are already available in the engine control unit. On account of the utmost stable, known coupling of the crank mechanism and the electrical machines by a belt drive, the pole wheel position and the rotational position of the crankshaft of the internal combustion engine are in a fixed, known ratio to each other.
When the internal combustion engine is turned off, the rotational position of the internal combustion engine can be recorded in the engine control unit and stored permanently.
The storage of the last instantaneous rotational position information may be written into a memory which retains this information even if current supply of the engine control unit is interrupted. During the next starting procedure of the internal combustion engine there is thus available an exact value for the crankshaft""s angular position of the internal combustion engine, so that the starting phase of an internal combustion engine may be drastically shortened by the omission of the search cycle.
Compared to design approaches used up to the present in the related art, by reverting to rotational position information gathered at the time of the previous shutting down of the internal combustion engine, the search cycle preceding the starting procedure is either made completely superfluous, so that the internal combustion engine may be started directly at the required torque, or the initial value for beginning the search cycle may be selected so that the search cycle is drastically shortened from a time point of view, and can be held small with respect to the angle swept over.
Thereby, an absolute angle encoder may be saved in the electrical polyphase machine, such as a high-output generator, which is to be synchronized with respect to the pole wheel position. Internal combustion engine and electrical three-phase machine are in a fixedly predefined coupling connection to each other, e.g. via a belt drive, which is held at the appropriate initial tension to exclude slippage. If the internal combustion engine is switched off, then, via the transmission ratio of the belt drive, the belt length, the diameter of the belt pulley of the electrical poly-phase machine as well as of the diameter of the belt pulley mounted laterally on the crankshaft, the pole wheel position is coupled to the position of the belt pulley on the crankshaft side. From this, the pole wheel position is able to be adjusted to the rotational position of the internal combustion engine in one balancing operation; since this operation takes place at a rotational speed n=0, the influences of the couplingxe2x80x94in the case of the belt drive selected here the appearance of slippagexe2x80x94is suppressed.